cross

#!/bin/bash
shopt -s expand_aliases

## git workflow to crips git repositories

## NOTESa
## to share features to upstream, commit on upstream branch with `cd patch; git cherry-pick ##### -Xtheirs`
## --untracked-files=no

W=. # git worktree
declare -a FETCHED=('')
export _gitpth=$(which git)

# DEFAULTS
export CROSS_DEFAULT_BRANCH=${CROSS_DEFAULT_BRANCH:-master}
export CROSS_REBASE_ORIGIN=${CROSS_REBASE_ORIGIN:-false} # to rebase local branch with origin
export CROSS_FETCH_DEPTH=${CROSS_FETCH_DEPTH:-20}
export MAGENTA='\033[0;95m'
export YELLOW='\033[1;33m'
export NC='\033[0m' # No Color'

# KEYWORD Fn available in Cross file
# setup git config
setup() {
  # require git >=2.20
  git config advice.addEmbeddedRepo false
  git config extensions.worktreeConfig true
  git worktree prune
}

# use, is virtual function for DSL like syntax to configure sources
# it add upstream as remote to tracking branch
use() {
  [[ -n "$1" ]] || say "USE called without an position argument 1: remote name"
  [[ -n "$2" ]] || say "USE called without an position argument 2: repository url"
  name=$1
  [[ $(git remote show | grep $name) ]] ||
    _git remote add $@
}

# remove, stop tracking a patched source
remove() {
  local branch=$(git --git-dir=.git/worktrees/$1 rev-parse --abbrev-ref HEAD)
  _git worktree remove --force $1
  _git branch --force -D $branch
}


# patch, track 'origin/path' as branch and checkout it to your git worktree
patch() {
  # origin:path/to/folder [path/in/my/repo] [-b branch]
  # core:habitat/corends coredns -b master

  local from=$1
  local orig=$(cut -d: -f1 <<<"$from") # origin repository `use` name in Cross file
  local opth=$(cut -d: -f2 <<<"$from") # path in origin repository
  local path=${2:-$opth}               # path in local repository
  local branch=${4:-$CROSS_DEFAULT_BRANCH} # branch/tag at origin

  local fdepth=${CROSS_FETCH_DEPTH}

  # skip already processed dependencies
  [[ "${FETCHED[*]}" =~ $path ]] && return 0

  # fixture
  local opth=${opth#/} # avoid leading slash
  local path=${path#/} # avoid leading slash

  # check existence of local branch tracking upstream
  _branch_exist() {
    git rev-parse --verify "$orig/$branch/$opth" &>/dev/null; [[ $? -eq 0 ]]
  }

  _rebase_active() {
    ( test -d "$(git rev-parse --git-path rebase-merge)" || test -d "$(git rev-parse --git-path rebase-apply)" ) 
  }

  if ! _branch_exist ; then # first time only
  # set tracking and fetch from remote/branch
    say "Tracking $orig:$opth (branch:$branch) at $path"
    _git fetch --prune --depth=$fdepth $orig $branch:$orig/$path
    [[ -e $W/$path ]] && mv $W/$path $W/$path.crossed # backup if exist locally
    # add worktree as branch per local path
    _git worktree add --no-checkout -B "$orig/$branch/$opth" $W/$path --track $orig/$branch
    pushd $W/$path
      sparse_checkout=$(git rev-parse --git-path info/sparse-checkout)
      # configure $name into info/sparse-checkout
      if ! [[ $(cat $sparse_checkout 2>/dev/null) =~ ^/$opth/ ]]; then # first time - configure
        _git config --worktree --bool core.sparseCheckout true
        _git config --worktree --path core.worktree $PWD/..
        _git config --worktree status.showUntrackedFiles no
        [[ -e $sparse_checkout ]] ||
          mkdir -p $(dirname $sparse_checkout)
        echo "/${opth}/" | tee -a $sparse_checkout >/dev/null
      fi
      _git checkout
    popd
    # add to revision history
    _git --git-dir=.git --work-tree=. add $W/$path

  elif [[ -e $W/$path && _branch_exist ]]; then
  # sync with upstream repo
    pushd $W/$path
    _git fetch --prune --depth=$fdepth $orig $branch
    if ${CROSS_REBASE_ORIGIN}; then
      say "$path ($orig)"
      git config --worktree status.showUntrackedFiles no
      _rebase_active && {
        COLOR=$YELLOW say "$W/$path is has rebase in progress. Skipped.";
      } || {
        # stash, rebase, pop
        _git --git-dir=$(sed 's/gitdir: //g' .git) stash clear
        _git --git-dir=$(sed 's/gitdir: //g' .git) stash -q
        _git rebase
        _git --git-dir=$(sed 's/gitdir: //g' .git) stash pop -q || true
      }
    fi
    popd
  fi

  FETCHED+=($path)

  # placeholder
  # cross_post_hook $path

}

# STAFF AROUND
_git() {
  ${VERBOSE:-false} && echo -e "${COLOR:-$YELLOW}git $@${NC}" || true
  $_gitpth "$@"
}
repo_is_clean() {
  git diff-index --quiet HEAD --
}
pushd() {
  export OLDPW=$PWD
  cd "$@" >/dev/null
}
popd() {
  cd - >/dev/null
}
say() {
  (echo >&2 -e "\n${COLOR:-$MAGENTA}$1${NC}")
  [[ -z ${2:-''} ]] || exit $2
}
ask() {
  local prompt default reply
  while true; do
    if [[ "${2:-}" =~ ^Y ]]; then
      prompt="Y/n"
      default=Y
    elif [[ "${2:-}" =~ ^N ]]; then
      prompt="y/N"
      default=N
    fi
    say "\n$1 [$prompt]"
    read reply
    reply=${reply:-$default}
    case "$reply" in
    Y* | y*) return 0 ;;
    N* | n*) return 1 ;;
    *) return 1 ;;
    esac
  done
}

# MAIN
# continues if not sourced
if [[ "$BASH_SOURCE" == "$0" ]]; then
  set -eu -o pipefail
  setup
  if [[ $# -gt 0 ]]; then
    # exec individual action
    fn=$1
    shift
    $fn $@
  else
    repo_is_clean || ask "There are uncommitted changes in the repository. Continue?" Y
    [ -e Cross* ] && source Cross* || echo "No Cross* file found"
  fi
fi